1. Field
The present invention relates generally to telecommunications systems, and more specifically to group call service in a code division multiple access (CDMA) radio access network over a core network.
2. Background
A class of wireless services intended for quick, efficient, one-to-one or one-to-many (group) communication has existed in various forms for many years. In general, these services have been half-duplex, where a user presses a “push-to-talk” (PTT) button placed on a phone or radio to initiate speech. Pushing the PTT button triggers a radio or a server, which indicates the user's request for the “floor.” If granted the floor, or granted talker status, the talker may speak for a while, after which the talker may release the PTT button, and the listeners may request the floor. Communication is generally from one talker to a group of listeners, or just to one listener. This kind of service has traditionally been used in applications where one person, or a “dispatcher,” needs to communicate to a group of people, such as field service personnel.
A key feature of these services is that communication is quick and spontaneous, usually initiated by simply pressing a PTT button without going through a typical dialing and ringing sequence. Communication in this type of service is generally very short, with individual talk spurts being generally on the order of 10 seconds or less, and conversations lasting from minutes to a whole business day, e.g. in the case of a radio taxi service.
One such service is the GSM voice group call service (VGCS), as described in the GSM system specifications such as 3GPP TS 42.068 “Voice Group Call Service (VGCS); Stage 1,” 3GPP TS 42.069 “Voice Group Call Service (VGCS); Stage 2,” and GSM 04.18 “Mobile radio interface layer 3 specification; Radio Resource Control Protocol”. It would be desirable to incorporate such a system in CDMA networks, which are rapidly overtaking GSM systems as the network of choice due to their technological superiority.
There is a need in the art for offering group call service (GCS) in CDMA systems.